Field of the Invention
The present invention relates to wireless communication, and more particularly, to a method of steering traffic in a wireless communication system and a device using the same.
Related Art
3rd Generation Partnership Project (3GPP) long term evolution (LTE), which is improved technology of Universal Mobile Telecommunications System (UMTS) has been introduced to 3GPP release 8. 3GPP LTE uses orthogonal frequency division multiple access (OFDMA) in a downlink and uses Single Carrier-frequency division multiple access (SC-FDMA) in an uplink. Nowadays, a discussion on 3GPP LTE-Advanced (LTE-A), which is improved technology of 3GPP LTE has been performed.
A wireless communication system may provide a service to a UE through a plurality of access networks. For example, the UE may receive a service from a 3GPP access network, which is a mobile wireless communication system and receive a service from a non-3GPP access network such as Worldwide Interoperability for Microwave Access (WiMAX) and a Wireless Local Area Network (WLAN).
While the UE establishes a connection with a 3GPP access network to receive a service, when a traffic overload occurs in the 3GPP access network, it may improve efficiency of an entire network that the UE processes traffic to process through another access network, i.e., a non-3GPP access network. In this way, traffic steering is referred to as steering of traffic or a path of traffic such that traffic may be variably processed through a 3GPP access network and/or a non-GPP access network.
For traffic steering, a policy for interworking of a 3GPP access network and a non-3GPP access network such as Access Network Discovery and Selection Functions (ANDSF) may be set to the UE, and the policy may be managed separately from an interworking policy set by the network.
When power is initially turned on, the User Equipment (UE) searches for an available public land mobile network (PLMN) and selects a suitable PLMN that may receive a service. The PLMN is a network disposed and operated by a mobile communication network operator. In each country, because a plurality of mobile communication network operators generally exist, a plurality of PLMNs may exist. The UE selects/registers a suitable PLMN and selects a cell having a signal quality and a characteristic in which the UE may receive a suitable service among cells in which the selected PLMN provides. The cell may steer traffic between a first method of network (e.g., 3GPP LTE/LTE-A) and a second method of network (e.g., wireless LAN) according to traffic. The cell provides policies/parameters for steering traffic between a first method of network and a second method of network, and the policies/parameters may be referred to as RAN assistance information.
However, each mobile communication network operator may share the cell in view of cost/efficiency/strategy. That is, a second mobile communication network operator (second PLMN) may share a cell operated by a first mobile communication network operator (first PLMN) and vice versa. In this case, because the cell is operated by the first mobile communication network operator, the cell may provide only optimized RAN assistance information to the first PLMN. Therefore, when a UE registered at the second PLMN accesses to the cell, the UE may not receive optimized RAN assistance information. Accordingly, efficiency of traffic steering may be deteriorated and resultantly, a system performance may be degraded.